Breech-block-operating mechanism



I April 28, 1931. G, M; MGCANN 1,802,727

BREECH BLOCK OPERATING MECHANISM Filed oct. 28, 1930 2 sheets-sheet 1 ANEW IN VEN TOR.

A TTORNEY April 28., 1931. G. M. MccANN BREECH BLOCK OPERATING MECHANISMFiled oct. 28, 195o 2 Smets-sheet 2 INVENTOR Eenrgle M MEEELTLVL ORNEYPatented Apr. 28, 1931 Y *Y UNITED STATES PATENT GFFICE i' I 'i l .GEQRGiviccAivN, or CASTLE, DELAWARE l i j BnijiEoH-BLocK-QPERATINGiviEoHAivisM i ppliieafnm` mea october 28,( ieo. sei-iai 'Nol 491,722.(GRANTED UNrER TiiEVACT or MARCH 3, 1883, as APRIL so, 1792s; 37o o. G.757)Y The :invention `described herein may be i IFig. 'l' is a View infront elevation ofthe Y manufactured and used by or for the- Govimprovedoperating mechanism;`

ernment for governmental purposes, With- 'F ig.. 2 is ar sectional vieWon the line 2.-2 out 'the .paymentto me f of any royalty of Fig.v l;l

. thereon. x Fig. 3 is a view in side elevationgand 50 The Vinventionrelates to a breech block partly in section of a breech block in' closedvoperating mechanism and is an improveposition and showing theeXtractors; ment on the type of mechanism shown in Fig. is a fragmentaryview showing the Patent No. 996,569 of'June 27, 19l1. vmanner in whichthe eXtractors and block .10 In'the patent a yielding Camarrngement,cooperate to hold they block in the open 55 is provided whereby the gunis allowed to POS1 10I1; f y recoil freely with the breech closed, butonY Flg- 5 1S a Similar View showing the posicounterrecoilthe cam iseffective to rotate tlOnOf the block vWhen the crank leaves acrank-Which Aopens' the block. During the Calngllldef the vfinal openingofthe block theV eXtraC- Referring t0 tneddWnlgSr byeneirnetels 6o torsare functioned as in Patent No.1 393 0f fefelfenee f 1353 0f-October 11,i921, to Withdraw? ihe I n F1a-'f3' there ls-shwngajgun 4 @f thecartridge 'case and Vlock the block .l in the feelPee-atlng typepfo'lded 73th 2j VA/11310211* open position. Frequent failure of the eX-15 Sndng bleeen bloei 5 WnlCnlS opened l 2o tractors'to hold-the blockopen has led'to and Closed by en opeetng ena-ft o' and 65.

' Y assuredly positioned before being; engaged "i" the details ofconstruction*,hereinafter der `the presentl improvement Which relates to*Crank* 7 in e Well known mennen *The Snaft the'block opening mechanismbut affects '.Carres a handle 8 *for manual Control and the functioningof theV extractor inholding 1S attached. to a Spmng mechemsm' 9 for".the block Open' Y closing the block. The. cartridge extrac- 'Accordingto the invention the block tors .l0 ere'ofthebtype Shown m the piments yOpening mechanismV isV modified tov Provide hereinbefore referred to andhave the inside amore gradual andv an "additional movefummo? llflattened as at 12 for engage Vinentof the block lwhereby a Vtimeinterval ment with a Shoulder 13T of the block Whore is obtained inWhich the extractors may be by -the' block 1S locked m Open Posltlon I Y(Fig-g4), the faces'll andlo of the eXtrac-r 75 torbeing in. Contactrespectively With the .gun 4- andthe block 6. A spring-pres`sed lplunger16- normally tends to hold the eX'- tractor in the locking position.Thetrun- .nien 11 is disposed in `acam groove 17 in 80 Y :the blocktand' a 'corresponding trunnion Sorlbed 2Lnd olenned 1t belngA1111defetood out :away-in Figs' and 4 is supported by that changes inthe precise embodiment o f the breech ring Off/Che 1m `the inventionherelll CllSClOSed may be made Referring to Figs. l andi 3 the left handby the block.

ith the foregoing andV other objects v in view, the" invention residesin the novel ar- .,5 rangement and combination of'parts' and in Y- 40Within the SCOpl` 0f What islllA-: Wthend of theoperating shaft 6carries acranlr 55 i ings, wherein:

outdeparting from the spirit ofthe'Vv inven- 18,7Which, inthe in batteryposition ofthe gun t10n. i is" positioned forwardly, of its -v actuatingA practical embodiment .of-,the invention mechanism.

vis illustratedini the accompanying draw- Thismechansrnfoonsstsessentiallydof a 'plate 191 having a largetrunnQn 20Lbut the action is not positive.

mounted in the manner shown in Patent No. 996,569 in a plate 21 securedto the cradle plate 22. The rotatable cam plate is provided withshoulders 23 and 24 engageable respectively with correspondingly shapedfaces 25 and 26 in the plate 21 whereby rotational movement of the camplate is limited. The shoulder 23 limits movement of the cam plate duetothe action of the spring 27 and the shoulder 24 limits movement due todepression of the cam plate when the head 28 of the crank 18 rides overthe upper face 29 of the cam during recoil of the gun; When theshoulder`23 is in engagement -with the face 25 the cam plate 19 isrigidly held so that the head 28 ofthe crank in riding along the lowerface 30 will cause the crank 18 and shaft 6 to be rotated to open thebreech block; i y Y- Y I Y A second cam plate 31 is rigidly secured tothe plate 21 by means of screws 32 which in turn are locked by setscrews 33. This fixed cam is in prolongation of the rotatable cam 19 andits rearmost end 34 preferably extends across the axis of rotation ofthe cam 19.` rIhe cam face 35 ofthe cam 31 is of less inclination thanthe lower face 30 of the rotatable cam and its origina is spaced aslight distance from the-termination ZJ of theface. 30.

In the normal position of the parts prior to firing the gun, the breechblock is closed as in Fig. 3 and the relation between the fixed androtatable cam is as shown in Fig. 1. The gun on lbeing fired movesrearwardly in recoil and the head 28V of the crank 18 rides over androcks the rotatable VAcam.

On counterrecoil of the gun the head 28 AVengages the lower face 30of-the cam and asa result the crank and the shaft 6 are rotated to openor lower the breech block against the action of the spring mechanism 9.Y

When the head 28 of the crank 18 is at the point b of the cam face 30thebreech block isinthe position shown in 4, the trunnion 11 of theextractor having left the cam groove 17 and in doing so causedretraction of the extractors. Up to this p oint the action closelyfollows that of the operating mechanismV shown in thepatents. It willbenoted that on retraction -of the extractors, the face 1.5 of theextractors strikes the breech'block and has a' tendency Vto reboundandvibrate, thereby angularly moving the flattened face 12 of the .trunnion"11 and also bodily displacing the trunnion to the rear. This vibrator-yaction is'supposed to be neutralized by .the'lspringpressed plunger 16(F ig. 1) 'which urges the lowerv portion of the extractors forwardly Asa consequence, if the lowering or holding/ of fthe lock is "discontinuedas "byjthe crank 18 learng'the @am 19, the spring mechanism 9 isimmediately effective to raise the block, and if the trunnion 11 is notfully forward to present its flattened face 12 parallel to the shoulder13 of the block, the block instead of being restrained by the extractorwill exert a camming action on the trunnion 11 and force it rearwardlyinto the slight'y and nmomentary raising of the block for the purpose ofallowing the shoulder 13 of the block to engage the flattened end 12 ofthe extractor trunnion'and serve to steady the extractor and reducevibration'to a minimum. The crank then rides down the face 35 of thefixed cam 31 to cause a further lowering of the breech block to theposition shown in Fig. 5 and provide Va time interval which' will insurethe correct positioning of the extractor` in a state of rest before theshoulder`13 of the rising breech 1'" block engages the flattened face 12of the extractor trunnion 11. The' breech block is free to be raisedbythe spring mechanism 49 when the crank clears thenon-inclinedface -36of the'xedr cam 31.

,IclaimwVV v Y 1; In a gun, the combination 'with a breech block, acrankshaft foroperating theblock Aand extractors for holding the blockopen,

of a cam arrangement including a rotatably mounted cam yielding-t0 theVcrank on recoil andv effective to rock thecrank on counter of theextractors, a xed cam in prolonga- Vtion`of the rotatable cam but spacedtherefrom, said fixed cam' effective. to rock the crank shaft to'lowerthe block below the position of its engagement with the extractors. n n

2. In a gun, the combination with a breech block, a crank shaft foroperating the block and extractors for holding the block'open, of VacamYarrangement including a rotatably Ymounted cam yielding-to the crank on'recoil and effective torock the crank on counter ;-y

3. ,In a gun, a breech block, a crank shaft "for operating the block,acam arrangement including a rotatably mounted cam yielding to the crankon recoil and eeetivetg'lrock 0f its engagement with vthe 'extractorathecrank on counter recoil, and a fixed cam in prolongation of thelrotatable cam and effective to additionally rock the crank shaft.

4. In a gun, a breech block, a crank shaft for operating the block, acam arrangement including a rotatably mounted cam yielding to the crankon recoil and effective to rock the crank` on counter recoil, and a Xedmember for stabilizing the cra-nk after it leaves the rotatable cam. f

GEORGE M. MCCANN.

